It is well known that heavy water or deuterium oxide (D.sub.2 O, or 2H.sub.2 O) is useful in nuclear magnetic resonance (NMR) spectrographic studies, such as those now widely used in biochemical research and in developing new applications for clinical research. An example of such prior art usage is in the measurement of total body water as it is associated with evaluations of acute and chronic alterations in hydration that can be caused by a variety of illnesses. In such methodology, the NMR signal of D.sub.2 O, or of a D.sub.2 O/H.sub.2 O solution, appears at a frequency that is distinctly different from all other frequencies of deuterium belonging to any molecular fragment, therefore an accurate estimation of D.sub.2 O in biological fluids is permitted. Such NMR spectroscopy methods are not, however, useful in providing in vivo NMR imaging of blood vessels and organs such as the heart, kidneys, liver, etc. of a patient.
There have been a number of earlier studies of the affect of heavy water on mammals. Theose studies involve either the ingestion of heavy water by the mammals, or occasionally a subcutaneous injection of heavy water into animals has been analyzed. So far as the present inventors are aware, those earlier studies did not involve any use of NMR imaging in connection with the ingestion or injection of heavy water into a living mammal patient.
In order to be useful for in vivo NMR imaging, a suitable imaging dye material must not resonate at the frequency of water hydrogen, and the dye material must not have an adverse affect on the patient's organs that are to be imaged with the method. In particular, the dye solution must be usable in a sufficient concentration for it to have a desirable level of effect on the NMR image. Thus, the use of solutions containing various radionuclides or other toxic substances are either severely limited or precluded from use as NMR imaging dyes for in vivo applications.